Identification of Genetic Defects Underlying FXII Deficiency in Four Unrelated Chinese Patients

Congenital factor XII (FXII) de&#xFB01;ciency is a rare autosomal recessive disorder, characterized by a great variability in its clinical manifestations. In this study, we screened for mutations in the<i> F12</i> gene of 4 unrelated patients with FXII coagulant activity <10% of that of normal human plasma. To investigate the molecular defects in these FXII-deficient patients, we performed FXII mutation screening. By sequencing all coding exons as well as flanking intronic regions of the <i>F12</i> gene, 6 different mutations, including 3 missense mutations (Gly341Arg, Glu502Lys and Gly542 Ser), 1 insertion (7142insertC) and 2 deletions (5741-5742 delCA and 6753-6755delACA), were identi&#xFB01;ed on the<i> F12</i> gene. Three of them (Gly341Arg, 5741-5742delCA and 6753-6755delACA) are reported here for the first time. Computer-based algorithms predicted these missense mutations to be deleterious. This study has increased our knowledge of the mutational spectrum underlying FXII deficiency.